Avian influenza (HPAI) season summary — how to read the official data
Highly pathogenic avian influenza (HPAI) returns in waves every year, most often in autumn and winter, alongside wild-bird migrations. We do not invent figures — we show the typical seasonal pattern and teach you how to read the official summaries of the Chief Veterinary Inspectorate (GIW) yourself. That way you know when the risk rises and how to turn data into decisions on your own farm.
verifiedFrom the team that has organised work on poultry farms for years.
What is avian influenza (HPAI)
Avian influenza, more precisely highly pathogenic avian influenza (HPAI), is a viral disease of birds that can cause massive and very rapid deaths in a poultry flock. It is fought by law — detecting an outbreak means culling the flock and setting up zones around the farm. That is why every farmer should understand how the disease spreads and when the risk is highest. We gather the basics of symptoms and course in the article on avian influenza (HPAI).
Why bird flu has its season
HPAI does not appear evenly throughout the year — it has a clear season. The peak usually falls in autumn and winter, because this is the time of wild waterfowl migrations (ducks, geese, swans, gulls), which are the natural reservoir of the virus. These birds carry the virus over long distances and leave it in the environment — in water, on fields, near reservoirs. Low temperatures help the virus survive outside the body, so pressure on farms rises precisely in the cold months.
Where the season data comes from
The official source of information on outbreaks in Poland is the Chief Veterinary Inspectorate (GIW). It publishes notices on confirmed outbreaks in poultry and in wild birds, zone maps and periodic summaries. European data is additionally collected by EFSA (the European Food Safety Authority). For live tracking there are tools updated in real time — the EFSA HPAI dashboard and WOAH WAHIS, the World Animal Health Information System. In this guide we deliberately do not quote specific outbreak figures for a given year — we show the pattern and teach you where and how to check the current, official data yourself.
Why read a season summary
A season summary is not trivia but a planning tool. When you know the period of heightened risk is starting, you tighten your poultry farm biosecurity in advance, check weak points and prepare your staff. Reading GIW data lets you react before the virus reaches your area, not only after the fact. That is the difference between a farm that defends itself and a farm that counts its losses.
From knowledge to action on the farm
Awareness of the season alone is not enough — it has to turn into concrete records and actions. DlaFerm.pl helps translate the season’s conclusions into practice: you build a biosecurity plan, test your team’s knowledge in the biosecurity quiz and keep daily flock observations in the digital Flock Card. That way knowledge about the season becomes real protection. You can create a farm account for free.
What an HPAI season looks like — the typical course
Every season is different, but a similar pattern returns. Here are six features that repeat year after year in the official GIW summaries — and that help you understand when and where the risk is highest.
Autumn-winter peak
Most poultry outbreaks are usually recorded from late autumn to early spring — most often between November and March. This coincides with migrations and the cold that helps the virus survive in the environment. The 2025/26 season was very intense in Europe — according to EFSA, more than two thousand HPAI detections were recorded in several dozen countries between November 2025 and February 2026. In summer the pressure usually weakens, although in recent years single outbreaks have also occurred outside the classic season. The season curve is best followed directly in GIW notices.
The role of wild waterfowl
The natural reservoir of the virus is wild waterfowl — ducks, geese, swans and gulls. They carry HPAI along migration routes and leave it in water and on fields. That is why poultry outbreaks often break out where wild birds had died earlier. Direct contact of poultry with wild birds, or with water and equipment contaminated by them, is one of the main routes of infection — which is why biosecurity matters so much.
The most vulnerable species
The disease affects all poultry, but the picture varies. Hens and turkeys fall ill severely, with sudden deaths. Ducks and geese can become infected and shed the virus even without clear symptoms, which makes them a dangerous link. The H5N1 virus keeps expanding its host range — since 2024 infections of dairy cattle (a spillover to mammals) have been confirmed in the USA, which shows the global, structural nature of the problem. Flocks kept with access to outdoor runs are more exposed than closed ones. The symptoms are easy to confuse with other diseases — compare them with the article on Newcastle disease (avian pseudo-plague).
Protection and surveillance zones
After an outbreak is confirmed, the district veterinary officer marks restricted areas around it: a protection zone (closest to the outbreak) and a wider surveillance zone. In these zones bans on moving poultry apply, along with mandatory flock censuses and increased oversight. GIW publishes the maps and extent of the zones — this is the first thing to check when an outbreak appears in your region.
Higher-risk regions
Risk is not spread evenly across the country. It tends to be higher where poultry farms are densely clustered and along bird migration routes — near large reservoirs, floodplains and wetlands. GIW and EFSA summaries usually show which regions were most affected in a given season. If your farm lies in such an area, treat the season more seriously and earlier.
Impact on the market and exports
An HPAI season is not only the loss of individual farms. Culling large flocks and restrictions in zones can temporarily shake the supply and prices of poultry and eggs. Detecting an outbreak also affects exports — some countries impose import restrictions from affected regions. That is why the scale of the season interests not only the veterinary services but the whole industry, and GIW notices are followed by buyers and processors too.
What the HPAI season means for your farm
Data is one thing, decisions another. Here are six takeaways every poultry farmer should draw from the season summary and put in place before the risk reaches the area.
Tighter biosecurity in season
When the period of heightened risk begins, tighten your protection rules: a fully closed flock, disinfection mats, entry control, separating clean and dirty zones and limiting vehicle access. In season additional requirements from regulations also apply — including keeping poultry under cover. The simplest way is to put it all in one document through the biosecurity plan generator.
Duty to report suspicions
Every suspicion of HPAI must be reported immediately to the district veterinary officer — it is a legal duty, not goodwill. Warning signs are a sudden rise in deaths, a drop in feed and water intake, nervous symptoms or a fall in lay. Do not wait for certainty — limiting the spread depends on a quick report. Teach this to your whole team, because the symptoms are usually first noticed by the flock staff.
Daily flock monitoring
In season, observing the flock matters more than ever. Note deaths, feed and water use and bird behaviour every day — a sudden change is the first signal. Records kept in real time let you catch an anomaly early and give hard evidence when reporting. The most convenient way is the digital Flock Card, where trends are visible at once rather than only after counting paper sheets.
A season plan prepared in advance
Do not start preparing when an outbreak is already nearby. Before the season, review the farm’s weak points, restock disinfectants, check the tightness of buildings and decide who does what in case of suspicion. A written action plan for HPAI shortens reaction time and limits chaos. It is the same thinking as with poultry farm biosecurity — better to prevent than to put out a fire.
Solid documentation
In the event of an outbreak and inspection, what you have written down counts: an entry log, disinfection treatments, flock observations, delivery data and deaths. Complete documentation is proof that the farm followed the rules, and the basis for any compensation for a culled flock. Paper chaos in a crisis costs time and nerves — keep records digitally and in real time, not from memory after the fact.
Using official GIW sources
In season information spreads fast, and much of it is rumour. Only official sources are reliable: GIW notices and maps, regulations and announcements of the district veterinary officer. There you check whether an outbreak is close and whether your farm has fallen into a zone. Also check that your team knows the rules — the biosecurity knowledge quiz helps with that. Base decisions on data, not on hearsay.
Frequently asked questions about the avian influenza season
When is the avian influenza season?add
The HPAI season usually falls in autumn and winter — most poultry outbreaks are recorded from late autumn to early spring, most often between November and March. This is due to wild waterfowl migrations and the cold that helps the virus survive in the environment. In summer the risk usually weakens, although in recent years single outbreaks have also occurred outside the classic season. The current course is best followed in GIW notices.
Where does the HPAI outbreak data come from?add
The official source in Poland is the Chief Veterinary Inspectorate (GIW), which publishes notices on confirmed outbreaks in poultry and wild birds, zone maps and summaries. At the European scale, data is collected by EFSA. Only these sources are reliable — information from social media or rumours should always be verified against an official notice.
Why do you not give a specific number of outbreaks?add
The number of outbreaks changes from season to season and from week to week, so any figure given here would quickly become outdated and could mislead. Instead we show the recurring seasonal pattern and teach you how to check the current, official GIW data yourself. This approach is durable and always leads to the real figures at the source.
How do wild birds bring the flu to farms?add
Wild waterfowl — ducks, geese, swans, gulls — are the natural reservoir of the virus and carry it along migration routes. They leave the virus in water, on fields and around reservoirs. Poultry become infected through direct contact with wild birds or indirectly — through contaminated water, feed, litter, equipment or staff footwear and clothing. That is why cutting the flock off from wild birds and strict biosecurity are crucial.
What should I do when an outbreak is near my farm?add
First check the GIW maps and the district veterinary officer’s announcements to see whether your farm is in a protection or surveillance zone, and follow the restrictions in force there. Tighten biosecurity to the maximum, limit vehicle access and the movement of people, increase flock observation and be ready to report any suspicion immediately. In the zones, bans on moving poultry and mandatory flock censuses apply.
How do I prepare the farm for the HPAI season?add
Start preparing before the season, not when an outbreak is already in the area. Review the farm’s weak points, seal buildings, restock disinfectants, draw up a biosecurity plan and assign tasks in case of suspicion. Train the team and keep daily flock monitoring with records. DlaFerm.pl helps tie this together: a biosecurity plan, a knowledge quiz for the team and a digital Flock Card with real-time observations in one place.
Get through the HPAI season calmly with DlaFerm.pl
Want to act with a plan during the bird flu season, not in panic? We will show you how DlaFerm.pl helps you run biosecurity and daily flock records — from the plan to observations in the Flock Card. Create a free farm account.
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